From time to time, someone in the media raises the question "is it better to use disposable nappies (diapers) or cloth ones?" As Tina and I are childless, we have not had to face this problem in person. However, the debate about the answer is a classic case (as in Operational Research) of identifying the system in which you have defined the problem. The family is isolated from the problem of waste disposal, and concentrates on the costs and time needed for using either cloth or disposable. The waste disposal contractor (often local government in the UK) is concerned about the cost of landfill and is not bothered about the family. Society is concerned (ideally) with the total impact of a baby's lifetime in nappies. In the developed world, the option seen in Africa and Asia of letting the child run around without any nappy does not exist.
The speaker on local radio yesterday was a waste disposal person, and from his position, cloth nappies are best. But that is simply to look at the subsystem. According to several websites, and written reports, the choice is too close to call. Cotton growing, manufacture and then washing of soiled items, cause so much environmental impact that it matches the impact of disposable nappies in landfill. I haven't seen this in the O.R. literature.
Coincidentally, the book that I am currently reading (Hungry City: How Food Shapes Our Lives by Carolyn Steel) alludes to a problem which I have not seen in the reasoned discussion of the choice. How easy is it to dry a lot of nappies in a small modern British house or flat? Carolyn Steel raised the question of modern homes which are designed with minimal space in the kitchen, and British building regulations allow construction of houses with very limited floor area. So I wonder whether the answer to the question depends on how big your home is? There's a research area!